# -*- coding: utf-8 -*-
"""
Created on Tue Oct 10 18:58:58 2023

@author: 楠川之木
"""

data = input('输入一个字符串')
d = dict()
for ch in data:
    d[ch] = d.get(ch,0)+1    
mostCommon = max(d.items(),key = lambda item:item[1])
print(mostCommon)
